It is known to connect a body tube to chassis members by various connection systems permitting vertical adjustment of a steering system. The most recent devices relate to brackets fastened on either side of a body tube in a plane passing through the steering-wheel axis, the brackets each being provided with an elastic block which is fastened on the chassis. These two elastic blocks thus constitute a substantially horizontal virtual articulation axis passing through the plane of the steering-wheel shaft. The steering wheel can thus be adjusted vertically by angular displacement relative to the virtual articulation axis. Other devices are also known in which a pivot pin is fixed on each side of the body tube so as to constitute a virtual articulation axis which is substantially perpendicular to the steering-wheel axis and defines a plane with the latter. Each of these pivot pins is mounted in a bearing which is fixed on the chassis. In this case also the steering wheel can be adjusted angularly by being turned around this virtual articulation axis.
These types of devices have the disadvantage of offering only a single virtual articulation axis, which is situated in the plane of the steering-wheel axis. Consequently, these devices entail mounting stresses which are not easily compatible with the positioning of steering systems in modern motor vehicles, in which large size is a major disadvantage. Moreover, these systems are relatively complex and fairly heavy, factors which increase the manufacturing cost of these assemblies accordingly.